1. Prior Art
At present, it is known that stuffed food, particularly sausages, are stuffed into a tripe or synthetic material (plastics) tube which then have to be "peeled" in order that the sausage may be packed.
Known processes are comparatively expensive and time consuming, since they require steps that are deleted by the use of the method of the invention. In fact, summarizing the present operation, the food material is stuffed into a very long synthetic tripe compacted into a cartridge and, once stuffed with paste, it is twisted in pre-determined regions to form a string of independent sausages, of a determined length, which are hung in cooking conveyors. After this operation, sausages are let to cool in order to subject them to the action of the peeling machines. I.e., the plastic sheath or casing (tripe) is removed for the final vacuum packaging thereof.
Known processes for manufacturing skinless stuffed food materials require four machines, namely: a) stuffer; b) twister and cooler; c) peeler and d) packager. Between the twisting and peeling steps, stuff such as sausages, large sausages, etc. are cooked. After cooking, the product is passed to the cooler and peeler, then conveyed to the packaging machine. Once packaging is ready, sausages are passed to the delivery section.
Due to the features of the known manufacturing process, a loss of about 8% in raw material is produced.
This conventional manufacturing line requires a minimum space of twelve meters long for the five processes mentioned, which results in an important investment in building and machinery.
Further, another disadvantage of traditional methods is the impossibility of obtaining absolute vacuum, due to the presence of a small amount of air contacting the product, which makes it perishable in a short time due to pollution reasons.
Technology has developed new packaging processes, but these improvements took place for packaging products in the form of granules, powder or liquids, wherein the quality control of the product to be packed is controlled by a dispenser device, and pressure exerted on a product to shape the package is not required.
Further, these processes are not continuous, but are of intermittent sequence. Therefore, their production capacity is seriously limited as compared to a continuous process.
In the specific case of German type sausages packaging, the possibility of a continuous process is difficult due to the cooking step, as well as due to the fact that the sausage paste takes the shape of the package, which requires certain pressure in the packaging step. This pressure is what determines that the cross section of the package be rendered uniform and, consequently, the product weight constant.
Also, another disadvantage in the continuous process is the requirement that the package forming the sausage is the final package directed to consumers in order to avoid pollution of the product, in case such product after being shaped and cooked is introduced into a final package.
U.S. Pat. No. 5,053,239 discloses a process and apparatus for manufacturing German type sausages, which describes producing the sausage directly into the final package, which then allows cooking the sausage paste thus packaged.
However, although the mentioned process affords an improvement over the known process, this process is of intermittent sequence and requires synchronism between feeding of the portions forming the sausage and the transversal closure means of the package. Since said patent does not show the machine for producing said sausage paste portions of a pre-determined size, it does not specify the way in which operation control is carried out to attain synchronism of the package cross closure means, we may consider this process inapplicable.
In fact, from the reading of the mentioned patent and drawings, it may be seen that feeding tubes 1 extend between peripheral channels of cylinders 14 and 15 up to the outlet port close to the molding means, comprised by rollers 4 and 5 which have elements transversely pressing the tubular packing portions without sausage paste. The specification of U.S. Pat. No. 5,053,239, also does not explain the way in which small portions of sausage paste are passed through a feeding tube or the means used in order that each sausage portion maintains a constant space with the respect to the following one. Further, for the transversal sealing of the film, the process requires that such region be free of sausage paste, this being an outstanding difference with the method of the instant invention.
Also known is the system provided by Argentine Patent No. 228,903, which comprises a discontinuous feeding system. This systems operates by feeding molding cavities between sheets which are longitudinally welded, but the cavities of which are communicated by minor channels, producing a zigzag travel between sheets, then the regions into which channels are included are sealed.
Several trials have demonstrated that it is very difficult to obtain proper operation of this process, since paste pressures and differences in passage sections, as well as the zigzag arrangement produce at least an effect braking displacement, which at least reduces production to non profitable limits.